1. Field of the Invention
The present invention relates to an automatic assembly machine and, more particularly, to a gripping system for use in an industrial robot.
2. Description of the Prior Art
The range of products which can be handled by automatic assembly machines has recently been expanded from hard and rigid materials to soft and pliable materials, such as electrical lead wires.
As shown in FIG. 6, generally, the gripping device located at the end of a robot arm 31 has a hand 32 having a chuck 33 composed of a pair of movable chuck claws 33a and 33b, and an object detecting sensor 35 composed of a light emitter 35a and a light receptor 35b.
According to the prior art gripping system, the hand 32 moves toward a free end portion 34b of the elongated object 34, such as a lead wire, with the chuck 33 being opened, and grips the object by closing the chuck 33 when the object detecting sensor 35 detects the free end portion 34b of the object 34.
However, when the object 34 extending perpendicularly, for example, from a circuit board is bent or curved at a portion remote from the fixed end due to the flexibility of the object 34, the gripping device employing the prior art gripping system often fails to grip the free end portion of the object 34.